1. Field of the Invention
The present invention relates to a board-connecting connector to allow a print circuit board to be inserted into a pair of elastic contact terminals with a low insertion force for connecting to the board-connecting connector.
2. Description of the Related Art
FIG. 21 shows a first embodiment of a conventional board-connecting connector (see Patent Document 1).
This board-connecting connector 71 is also referred to as a card edge connector. The card edge connector 71 includes: one connector 74 in which a card edge, namely, an end of a print circuit board 72 is projected into an interior of a connector fitting chamber of a connector housing 73; and the other connector 78 having a pair of elastic contact terminals 75 for holding the print circuit board 72 in a board thickness direction, a pair of inner housings 76 for receiving the elastic contact terminals 75, and an outer housing 77 for receiving the inner housings 76.
A pair of upper and lower slope walls 79 are formed on a rear side of an inside of the connector housing 73. A spring 80 pushes top ends of the inner housings 76 in an opening direction. When the connectors 74, 78 are connected to each other, the top ends of the inner housings 76 are closed while sliding on the slope walls 79. Thus, inner elastic contact terminals 75 contact terminal parts of the print circuit board 72. Because a pair of inner housings 76 are open at a beginning of a connection of the connector 71, the connection is carried out with a low connection force.
FIG. 22 shows a second embodiment of the conventional board-connecting connector (see Patent Document 2).
This board-connecting connector 81 includes: a coil spring 84 connected to an outer terminal 83 at an inside of a connector housing 82 made of insulating synthetic resin; a toggle switch 85 pushed forward by the coil spring 84; and a pair of upper and lower elastic contact terminals 86 fixed to conducting parts of the toggle switch 85, projected outward when the connector 81 is not connected, and received in the connector housing 82 when the connector 81 is connected.
When the end of a circuit board 87 is inserted into an interior of the connector housing 82, the circuit board 87 pushes the toggle switch 85. Then, the toggle switch 85 and the elastic contact terminals 86 are moved backward, and then the pair of elastic contact terminals 86 hold the circuit board 87 in the connector housing 82. Because the elastic contact terminals 86 are open at the beginning of the insertion of the circuit board 87, the circuit board 87 is inserted with low insertion force.
For locking the circuit board 87 on the board-connecting connector 81, it is disclosed that holes (not shown) are formed on the circuit board 87, and projections (not shown) for engaging with the holes are formed at top ends of the pair of elastic contact terminals 86.
FIG. 23 shows a third embodiment of the conventional board-connecting connector (see Patent Document 3).
This board-connecting connector 88 includes: a connector housing 91 having a slit 90 into which an end of a circuit board 89 is inserted; and a lever 92 rotatably mounted on the connector housing 91 for fixing and releasing the circuit board 89.
After the circuit board 89 is inserted into the wide slit 90 with a low insertion force and freely fitted into the connector housing 91, the lever 92 is rotated inward to make a wedge board 92a push and hold the circuit board 89 toward an inner wall of the connector housing 91, and to engage a hole 93 of the circuit board 89 with a projection 94 of the connector housing 91. When the lever is rotated outward, a pushing board 92b of the lever 92 pushes the circuit board 89 in a releasing direction.
[Patent Document 1] Japanese Published Patent Application No. H8-37065 (FIGS. 2 to 4)
[Patent Document 2] Japanese Published Patent Application No. H8-236200 (FIG. 1 (a), (b))
[Patent Document 3] Japanese Published Patent Application No. H8-69836 (FIGS. 5 and 6)
However, in the first conventional embodiment (FIG. 21), the print circuit board 72 is inserted with low insertion force at the beginning of the connection, but at the end of the connection, the top end of the inner housings 76 frictionally slides on the slope walls 79 of the mating connector housing 73. Therefore, there is a problem that the insertion force may be increased due to the friction.
Further, in the second conventional embodiment (FIG. 22), only bending force of the elastic contact terminals 86 holds the circuit board 87. Therefore, when a thickness of the circuit board 87 is changed, the bending force is changed. Therefore, there is a problem that the board-connecting connector 81 is not adapted to the circuit boards 87 having various thicknesses. Further, when the circuit board 87 becomes thin after connection as a result of heat or the like, the bending force is changed and the circuit board 87 may not be sufficiently held.
Further, in the second conventional embodiment (FIG. 22), if lengths of the elastic contact terminals 86 are varied when the circuit board 87 is locked on the elastic contact terminals 86, the projection (not shown) at the top end of the elastic contact terminals 86 is not engaged with the hole (not shown) of the circuit board 87. Therefore there is a problem that the circuit board 87 may not be locked on the elastic contact terminals 86.
Further, in the third conventional embodiment (FIG. 23), because an inner width of the slit 90 of the connector housing 91 is predetermined, the locking projection 94 may be caught by the top end of the circuit board 89. Therefore, there is a problem that the circuit board 89 may not be smoothly inserted. Further, if the projection 94 is not bent, the projection 94 may not be engaged with the hole 93. For avoiding this problem, overlapping depth between the projection 94 and the hole 93 becomes small. Therefore, there is a problem that the locking force may be reduced.
Accordingly, an object of the present invention is to provide a board-connecting connector which allows a circuit board to be inserted thereinto with low insertion force from the beginning to the end of the insertion, allows a good contact pressure even when a thickness of the circuit board is varied, and allows the circuit board to be securely locked.